The epidemiology of failure in total knee arthroplasty

Complications following total knee arthroplasty in patients with prior extensor mechanism dysfunction: A retrospective review

Background

Extensor mechanism disruption following total knee arthroplasty (TKA) is a rare, yet serious complication. While previous patellar abnormalities are a theoretical risk factor for this complication, there is a scarcity of literature describing the impact of prior extensor mechanism dysfunction (EMD) on this and other complications following TKA. In this study, we describe our institutional experience with complications following TKA after EMD.

Methods

Sixty-one knees that underwent total knee arthroplasty between April 2007 and April 2023 in patients with previous EMD were identified. Extensor mechanism dysfunction types included patellar fracture, patellar tendon rupture, patellar realignment surgery, previous patellar dislocation, and a chronic laterally tracking patella impacting extensor mechanism function. Primary outcomes included extensor mechanism failure, infection, dislocation, aseptic loosening, revision surgery, and stiffness requiring manipulation under anesthesia (MUA).

Results

A total of 61 knees, comprised of 53-patients, were included. There were complications witnessed in fifteen patients, leading to a 24.6 % overall complication rate. There was one extensor mechanism disruption in the form of a partial quadriceps tendon tear requiring repair. There was one patellar dislocation requiring reoperation. There were five superficial infections successfully treated non-operatively and four deep infections requiring reoperation. A total of nine reoperations were performed, four of which were revisions. Four patients underwent MUA due to severe post-operative stiffness.

Conclusion

In this study, we found a high complication rate following TKA in patients with previous extensor mechanism dysfunction. There was one case of partial quadriceps tendon rupture requiring repair.

Increased Involvement of Staphylococcus epidermidis in the Rise of Polymicrobial Periprosthetic Joint Infections

BACKGROUND

In this study, we aimed to analyze the temporal distribution of polymicrobial periprosthetic joint infections (PJIs), while also evaluating the patient risk factors associated with these infections following total joint arthroplasty at our institution across 2 distinct periods.

METHOD

This retrospective cross-sectional study evaluated 259 patients who had knee or hip PJI from 2001 to 2006 and 2018 to 2022. A PJI was diagnosed using the 2018 International Consensus Meeting criteria. We utilized the Polymicrobial Pathogens' Co-occurrence Network Analysis, a novel approach that leverages network theory to map and quantify the complex interplay of organisms in PJIs.

RESULTS

Of the 259 patients who had polymicrobial PJI, 58.7% were men, with mean age 67 years (range, 24 to 90). Of the 579 identified pathogens, Staphylococcus epidermidis was the most common (22.1%), followed by Staphylococcus aureus (9.0%) and Cutibacterium acnes (7.8%). The co-occurrence analysis indicated that Staphylococcus epidermidis frequently coexisted with Cutibacterium acnes (26 cultures) and Staphylococcus capitis (22 cultures). A notable increase in body mass index from 27.7 ± 4.4 in 2001 to 2006 to 29.7 ± 6.2 in 2018 to 2022 was observed (P = .001). Moreover, infections from Staphylococcus epidermidis, Cutibacterium acnes, and Staphylococcus capitis saw a significant uptick (P < .001).

CONCLUSIONS

The study shows that from 2001 to 2022, there was a significant change in the pathogens responsible for polymicrobial PJIs, particularly an increase in Staphylococcus epidermidis, Cutibacterium acnes, and Staphylococcus capitis. Alongside these microbial changes, there was a rise in body mass index and shifts in comorbid conditions, such as more renal disease and fewer cases of congestive heart failure. These changes highlight the dynamic interplay between host and microbial factors in the pathogenesis of polymicrobial PJIs, necessitating adaptive strategies in both surgical and postoperative care to mitigate the rising tide of these complex infections.

Vitamin E Cup Cross-linked Polyethylene in Total Hip Arthroplasty: A Meta-analysis of Randomized Controlled Trials

INTRODUCTION

The goal of this study was to assess the efficacy and safety of vitamin E cup cross-linked polyethylene (VEPE) liners compared with standard polyethylene (PE) liners in total hip arthroplasty.

METHODS

A systematic search of the PubMed, EMBASE, Scopus, and Cochrane Collaboration Library databases was conducted. The evaluated outcomes were radiological parameters, functional scores (Harris Hip Score, Numeric Rating Scale, and Activity Scale from the University of California), and adverse events. Odds ratios and mean differences (MD) were calculated for the dichotomous and continuous variables. Meta-analysis was done using Review Manager.

RESULTS

Seven randomized controlled trials (n = 990) were included. VEPE liners showed markedly lower penetration at the last follow-up (MD, -0.15; 95% confidence interval [CI], -0.18 to -0.11) and penetration rate at last follow-up (MD, -0.01; 95% CI, -0.01 to -0.00) than standard PE liners. However, no notable differences were observed in cup migration, inclination, anteversion, or patient-reported outcomes. The complication rate was not markedly different between the groups (odds ratio, 1.07; 95% CI, 0.42 to 2.73).

DISCUSSION

This meta-analysis found that while VEPE demonstrated decreased penetration rates in total hip arthroplasty, no differences were observed in patient outcomes or complications compared with standard PE. However, the clinical relevance of penetration rate reduction remains uncertain, given the short follow-up period.

Multicenter Randomized Clinical Trial of Highly Cross-Linked Polyethylene Versus Conventional Polyethylene in 518 Primary TKAs at 10 Years

BACKGROUND

Second-generation highly cross-linked polyethylene (HXLPE) has revolutionized total hip arthroplasty. However, the long-term risks and benefits of HXLPE in primary total knee arthroplasty (TKA) remain unknown. This randomized clinical trial evaluated implant survivorship, complications, radiographic results, and clinical outcomes of HXLPE and conventional ultra-high molecular weight polyethylene (UHMWPE) inserts in primary TKAs.

METHODS

We enrolled 518 patients (518 knees) who underwent primary TKA in 3 centers within 1 tertiary referral network. The mean age was 67 years, the mean body mass index was 32 kg/m2, and 58% of the patients were women. All of the patients underwent primary TKA with a cemented posterior-stabilized tibial insert and patellar resurfacing. Randomization proceeded via stratified dynamic allocation. The patients were blinded to their study group allocation: those in the control group (254 knees) underwent TKA with an UHMWPE insert (N2Vac; Stryker); those in the treatment group (264 knees) received an HXLPE insert (X3; Stryker). Kaplan-Meier survivorship, radiographic results, and clinical outcomes were assessed. This trial was registered with ClinicalTrials.gov. The mean follow-up was 11 years.

RESULTS

The 10-year overall survivorship free from any revision and from any reoperation was 96% and 94%, respectively. There were no differences in the risk of revision or reoperation between the groups (p > 0.05). There were a total of 19 revisions. Revision indications included periprosthetic joint infection (14 knees), instability (4 knees), and open reduction and internal fixation (ORIF) for a patellar fracture due to osteolysis around a UHMWPE insert (1 knee). There were no revisions due to polyethylene wear, osteolysis, or fracture of the post in the HXLPE group. The radiographic results and clinical outcomes were otherwise similar.

CONCLUSIONS

Notably, no wear-related failures were identified in the HXLPE group, but there was 1 case of osteolysis in the UHMWPE group.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Outcomes of Obese Patients Undergoing Primary Total Knee Arthroplasty: Trends Over 30 Years

BACKGROUND

The rates of obesity among patients undergoing total knee arthroplasty (TKA) have substantially increased. In addition, obesity is a well-established risk factor for complications after TKA. The purpose of this study was to analyze trends in body mass index (BMI) and complication risk among obese patients undergoing primary TKA treated at a single institution over 3 decades.

METHODS

Utilizing an institutional total joint registry, 13,919 primary TKAs performed to treat osteoarthritis between 1990 and 2019 were identified. Patients were stratified by BMI according to the World Health Organization (WHO) classification into 3 groups: non-obese (BMI, <30 kg/m 2 ), WHO Class-I and II obese (BMI, 30 to 39.9 kg/m 2 ), and WHO Class-III obese (BMI, ≥40 kg/m 2 ). Trends in BMI and survivorship free from reoperation, revision, and periprosthetic joint infection (PJI) were analyzed over time while controlling for age, sex, and the Charlson Comorbidity Index.

RESULTS

Over the study period, there was a 90% increase in the prevalence of Class-II obesity (13% to 25%) and a 300% increase in Class-III obesity (3% to 12%). Analysis of the entire cohort demonstrated a decrease in the 2-year risk of any reoperation, any revision, and PJI (p < 0.05 for all) with time. The risk decreased significantly over time for non-obese patients for any reoperation (p = 0.029) and any revision (p = 0.004) and for Class-III obese patients for any reoperation (p = 0.038) and any revision (p = 0.012), but it remained stable for Class-I and II obese patients. The risk of PJI decreased from 1990 to 2019 for non-obese patients (p = 0.005), but there were no significant changes in PJI risk for any obesity group.

CONCLUSIONS

Despite increasing rates of obesity among our patients who underwent TKA, we observed decreasing risks of reoperation, revision, and PJI over time. The risks of reoperation and revision declined among non-obese patients, remained stable for Class-I and II obese patients, and declined for Class-III obese patients. The PJI risk declined for non-obese patients over the study period, but no such decline occurred for any category of obesity. Despite the decreasing risks of reoperation and revision, further work is needed to improve PJI risk in obese patients.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Comparing a robotic imageless second-generation system to traditional instrumentation in total knee arthroplasty: A matched cohort analysis

Introduction

Robotic-assisted total knee arthroplasty (rTKA) has gained interest from patients and surgeons alike. Robotic systems assist with gap balancing and bone cut accuracy, which can theoretically minimize post-operative pain by decreasing soft tissue damage. This study compared perioperative results, 30- and 90-day complications, patient-reported outcomes (PROs), and survivorship to all-cause revisions between patients undergoing traditional versus rTKA.

Methods

A total of 430 TKAs (215 rTKA, 215 traditional) by two fellowship trained arthroplasty surgeons were retrospectively reviewed from 2017 to 2022. All rTKAs were performed using the CORI Surgical System (Smith & Nephew, Memphis, Tennessee). Cohorts were propensity score matched by age, sex, body mass index, and American Society of Anesthesiologist classification. Blood loss, surgical times, length of stays, 30- and 90-day complications, pain scores and PROs were compared with univariable analyses. Cox regression analyses evaluated survival to all-cause revisions.

Results

Patients undergoing rTKA had a higher incidence of discharge home (86.5 %-60.0 %) (p < 0.01). There was no difference in blood loss or surgical time. rTKA pain scores were lower in-hospital mean 2 (range, 0 to 9) vs 3 (range, 0 to 9) (p = 0.02) as well as at one-year post-operatively, mean 1 (range, 0 to 7) vs 2 (range, 0 to 10) (p = 0.02). Cox hazard ratio demonstrated no difference in survival to all-cause revisions (HR 1.3; CI 0.5 to 3.7) (p = 0.64).

Conclusion

This matched cohort analysis demonstrated potential short-term benefits associated with imageless second generation rTKA including improved early post-operative pain, without compromising survivorship to all-cause revisions.

Linear and Volumetric Polyethylene Wear Patterns after Primary Cruciate-Retaining Total Knee Arthroplasty Failure: An Analysis Using Optical Scanning and Computer-Aided Design Models

(1) Background: Analyses of retrieved inserts allow for a better understanding of TKA failure mechanisms and the detection of factors that cause increased wear. The purpose of this implant retrieval study was to identify whether insert volumetric wear significantly differs among groups of common causes of total knee arthroplasty failure, whether there is a characteristic wear distribution pattern for a common cause of failure, and whether nominal insert size and component size ratio (femur-to-insert) influence linear and volumetric wear rates. (2) Methods: We digitally reconstructed 59 retrieved single-model cruciate-retaining inserts and computed their articular load-bearing surface wear utilizing an optical scanner and computer-aided design models as references. After comprehensively reviewing all cases, each was categorized into one or more of the following groups: prosthetic joint infection, osteolysis, clinical loosening of the component, joint malalignment or component malposition, instability, and other isolated causes. The associations between volumetric wear and causes of failure were estimated using a multiple linear regression model adjusted for time in situ. Insert linear penetration wear maps from the respective groups of failure were further processed and merged to create a single average binary image, highlighting a potential wear distribution pattern. The differences in wear rates according to nominal insert size (small vs. medium vs. large) and component size ratio (≤1 vs. >1) were tested using the Kruskal-Wallis test and the Mann-Whitney test, respectively. (3) Results: Patients with identified osteolysis alone and those also with clinical loosening of the component had significantly higher volumetric wear when compared to those without both causes (p = 0.016 and p = 0.009, respectively). All other causes were not significantly associated with volumetric wear. The instability group differentiated from the others with a combined peripheral antero-posterior wear distribution. Linear and volumetric wear rates showed no significant differences when compared by nominal insert size (small vs. medium vs. large, p = 0.563 and p = 0.747, respectively) or by component (femoral-to-insert) size ratio (≤1 vs. >1, p = 0.885 and p = 0.055, respectively). (4) Conclusions: The study found increased volumetric wear in cases of osteolysis alone, with greater wear when combined with clinical loosening compared to other groups. The instability group demonstrated a characteristic peripheral anterior and posterior wear pattern. Insert size and component size ratio seem not to influence wear rates.

Robotic assistance improves success of cementless component fixation in one total knee arthroplasty system

INTRODUCTION

New cementless implant designs in total knee arthroplasty (TKA) have begun to shift the longstanding practice of cemented fixation. With aseptic loosening a leading cause for revision of cementless implants, initial osteointegration is critical for component survivorship. Robotic-assisted TKA (RA-TKA) has shown promising results in recent literature at improving component accuracy. The current study aims to evaluate if robotic assistance affects the success of cementless fixation in primary TKA.

METHODS

445 cementless primary TKA components from one manufacturer implanted by five surgeons between June 2018 and October 2022 were retrospectively reviewed. Those with minimum one-year follow-up were analyzed. Femoral and tibial components were reviewed separately and grouped based on whether manual or RA-TKA from the same manufacturer was performed. Fisher's exact test was used to analyze if aseptic loosening rates were different between the two techniques.

RESULTS

373 (82%) cementless components from a single knee system were included. 146 femoral and 103 tibial components were implanted using RA-TKA, while 63 femoral and 61 tibial components were implanted manually. At a mean follow-up of 18 months (range, 12 to 51 months), successful fixation was achieved in 96.2% of all components. No femoral components from either group were revised due to aseptic loosening. Four manually implanted vs. no robotically assisted tibial components were revised due to aseptic loosening (6.6% vs 0.0%; P = 0.038).

CONCLUSION

The performance of modern cementless femoral components was excellent with or without robotic assistance, however RA-TKA improved the survivorship of the same system's cementless tibial component.

LEVEL OF EVIDENCE

Level III.

Unexpected positive cultures in aseptic revision hip and knee arthroplasty

Aims

The outcomes of patients with unexpected positive cultures (UPCs) during revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) remain unknown. The objectives of this study were to establish the prevalence and infection-free implant survival in UPCs during presumed aseptic single-stage revision THA and TKA at mid-term follow-up.

Methods

This study included 297 patients undergoing presumed aseptic single-stage revision THA or TKA at a single treatment centre. All patients with at least three UPCs obtained during revision surgery were treated with minimum three months of oral antibiotics following revision surgery. The prevalence of UPCs and causative microorganisms, the recurrence of periprosthetic joint infections (PJIs), and the infection-free implant survival were established at minimum five years' follow-up (5.1 to 12.3).

Results

Of the 297 patients undergoing aseptic revisions, 37 (12.5%) had at least three UPCs obtained during surgery. The UPC cohort included 23 males (62.2%) and 14 females (37.8%), with a mean age of 71.2 years (47 to 82). Comorbidities included smoking (56.8%), hypertension (48.6%), diabetes mellitus (27.0%), and chronic renal impairment (13.5%). The causative microorganisms included Staphylococcus epidermidis (49.6%), Bacillus species (18.9%), Micrococcus species (16.2%), and Cutibacterium acnes (16.2%). None of the study patients with UPCs developed further PJIs or required further surgical intervention during follow-up.

Conclusion

The prevalence of UPCs during presumed aseptic revision THA and TKA was 12.5%. The most common causative microorganisms were of low virulence, and included S. epidermidis, Bacillus species, Micrococcus species, and C. acnes. Microorganism-specific antibiotic treatment for minimum three months' duration of UPCs in presumed aseptic revision arthroplasty was associated with excellent infection-free implant survival at mid-term follow-up.

A Comparison of Clinical Outcomes After Total Knee Arthroplasty in Patients Who Have and Do Not Have Self-Reported Nickel Allergy: Matched and Unmatched Cohort Comparisons

BACKGROUND

The impact of a preoperative self-reported nickel allergy in patients undergoing primary total knee arthroplasty (TKA) remains unclear. The aim of this study was to compare the revision rates and outcomes of patients who have a self-reported nickel allergy undergoing primary TKA to patients who do not have a self-reported nickel allergy.

METHODS

Over 5 years, a total of 284 TKAs in patients who have and 17,735 in patients who do not have a self-reported nickel allergy were performed. Revision rates and differences in preoperative and postoperative patient-reported outcome measures, including Knee Osteoarthritis Outcome Score Joint Replacement (KOOS JR), Visual Analog Scale, Lower Extremity Activity Scale, and the Patient-Reported Outcomes Measurement Information System Mental and Physical Scores, were compared.

RESULTS

Survivorship free of all-cause revision at 1 year was similar for patients who have and do not have a self-reported nickel allergy (99.5% [95% CI (confidence interval): 98.6 to 100.0] versus 99.3% [95% CI: 99.1 to 99.4]), P = .49). Patients who have a self-reported nickel allergy undergoing primary TKA had no difference in KOOS JR, Visual Analog Scale, or Lower Extremity Activity Scale scores at 6 weeks and 1 year and slightly worse Patient-Reported Outcomes Measurement Information System mental and physical scores at 6 weeks compared to patients who did not have an allergy. Matched analysis revealed no difference in 6-week or 1-year KOOS, JR scores between patients who did and did not have a self-reported nickel allergy when stratified by implant class (nickel-free versus standard cobalt-chromium) (P = .113 and P = .415, respectively).

CONCLUSIONS

Patients who have a self-reported nickel allergy can be advised that, on average, their clinical outcome scores will improve similarly to patients who do not have a self-reported nickel allergy, and revision rates will be similar.

The Microbiology of Knee Prosthetic Joint Infection and its Influence on Persistent Infection

Periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) is a severe complication causing a significant burden. The study aims were to establish the epidemiology of microorganisms in TKA PJI, the rate of persistent infection requiring further surgery, and the risk factors for this. Microbiological specimens between June 2002 and March 2017 at five regional hospital sites were identified with revision TKA procedures in the National Joint Replacement Registry. The time between procedures, type of revision strategy, and any subsequent further revision operations were collected. At minimum 2-year follow-up, 174 revision TKA were identified, with a mean patient age of 69 ± 11 years. A broad range of pathogens were identified. Fifty cases (29%) had persistent infection requiring at least one further operative procedure, 13 cases required 3 or more. Coagulase-negative Staphylococcus species (CNS) was seen most with failed surgery, polymicrobial infections also posing a significant risk factor. The best chance of a successful PJI surgical strategy was < 12 months from primary TKA, with the greatest risk between 3 and 5 years (p < 0.05). Younger age significantly increased the risk of further surgery (p < 0.05). Management varied; 103 (59%) debridement, antibiotic therapy and implant retention, with further surgery in 29%; 45 (17%) single-stage revision, with further surgery in 13%; and 26 (15%) two-stage revision, with further surgery in 12%. This study presents the most common causative pathogens for PJI in TKA, and the high rate of persistent infection after initial revision surgery. Risk factors for persistent infection and further revision surgery were polymicrobial and CNS infections, patients who presented between 3 and 5 years following primary TKA, and younger age. This study therefore raises important risk factors and areas for future research to reduce the burden of multiple operations after PJI.

Suspension-Sprayed Calcium Phosphate Coatings with Antibacterial Properties

Prosthesis loosening due to lack of osteointegration between an implant and surrounding bone tissue is one of the most common causes of implant failure. Further, bacterial contamination and biofilm formation onto implants represent a serious complication after surgery. The enhancement of osteointegration can be achieved by using bioconductive materials that promote biological responses in the body, stimulating bone growth and thus bonding to tissue. Through the incorporation of antibacterial substances in bioconductive, biodegradable calcium phosphate (CaP) coatings, faster osteointegration and bactericidal properties can be achieved. In this study, Cu-doped CaP supraparticles are spray-dried and suspension-sprayed CaP ceramic coatings with antibacterial properties are prepared using high-velocity suspension flame spraying (HVSFS). The objective was to increase the coatings' porosity and investigate which Cu-doped supraparticles have the strongest antibacterial properties when introduced into the coating layers. Biocompatibility was tested on human Osteosarcoma cells MG63. A porosity of at least 13% was achieved and the supraparticles could be implemented, enhancing it up to 16%. The results showed that the addition of Cu-doped supraparticles did not significantly reduce the number of viable cells compared to the Cu-free sample, demonstrating good biocompatibility. The antimicrobial activity was assessed against the bacterial strains Escherichia coli and Staphylococcus aureus, with Safe Airborne Antibacterial testing showing a significant reduction in both Gram-positive and Gram-negative strains on the Cu-doped coatings.

Effect of pH and hydroxyapatite-like layer formation on the antibacterial properties of borophosphate bioactive glass incorporated poly(methyl methacrylate) bone cement

Infection is a leading cause of total joint arthroplasty failure. Current preventative measures incorporate antibiotics into the poly (methyl methacrylate) (PMMA) bone cement that anchors the implant into the natural bone. With bacterial resistance to antibiotics on the rise, the development of alternative antibacterial materials is crucial to mitigate infection. Borate bioactive glass, 13-93-B3, has been studied previously for use in orthopedic applications due to its ability to be incorporated into bone cements and other scaffolds, convert into hydroxyapatite (HA)-like layer, and enhance the osseointegration and antibacterial properties of the material. The purpose of this study is to better understand how glass composition and change in surrounding pH effects the composite's antibacterial characteristics by comparing the incorporation of 30% wt/wt 13-93-B3 glass and pH neutral borophosphate bioactive glass into PMMA bone cement. We also aim to elucidate how HA-like layer formation on the cement's surface may affect bacterial adhesion. These studies showed that 13-93-B3 incorporated cements had significant reduction of bacterial growth surrounding the composite beyond 24 h of exposure when compared to a neutral borate bioactive glass incorporated cement (p < 0.01) and cement only (p < 0.0001). Additionally, through soaking cement composites in simulated body fluid and then exposing them to a bioluminescent strand of staphylococcus aureus, we found that the presence of a HA-like layer on the 13-93-B3 or pH neutral glass incorporated cement disks resulted in an increase in bacterial attachment on the composite cement's surface, where p < 0.001, and p < 0.05 respectively. Overall, our studies demonstrated that borate bioactive glass incorporated PMMA bone cement has innate antimicrobial properties that make it a promising material to prevent infection in total joint arthroplasties.

Is 18F-fluoride PET/CT an Accurate Tool to Diagnose Loosening After Total Joint Arthroplasty?

BACKGROUND

Several studies using positron emission tomography (PET) show highly elevated periprosthetic bone uptake of fluorine-18 sodium fluoride (18F-fluoride), suggestive of implant loosening after arthroplasty. Focus so far has been on qualitative but not on quantitative assessment. There is also a lack of intraoperative confirmation of preoperative 18F-fluoride PET findings. Although the method seems to have acceptable accuracy and high sensitivity, an attempt to improve the specificity and an overall validation of the method appear warranted.

QUESTIONS/PURPOSES

(1) Is there a difference in 18F-fluoride uptake around loose versus well-fixed THA and TKA components? (2) Can 18F-fluoride uptake measures provide a threshold that differentiates loose from well-fixed implants undergoing revision for a variety of septic and aseptic indications? (3) In a population restricted to THA and TKA undergoing revision for aseptic indications, can measurement of 18F-fluoride uptake still distinguish loose from well-fixed components? (4) What is the interrater reliability of measuring 18F-fluoride uptake?

METHODS

This was a retrospective assessment of a diagnostic test, 18F-fluoride PET/CT, which was performed prior to revision surgery. We included 63 patients with 31 THAs and 32 TKAs. Sixty-five percent of patients were female, and the mean age at 18F-fluoride PET/CT was 66 years. The THA had different modes of fixation (cemented, cementless, and hybrid; 45%, 32%, and 23%, respectively), whereas all TKAs were cemented. Imaging was conducted using routine protocols 1 hour after tracer injection. The interobserver reproducibility was analyzed using Spearman rank correlations and Bland-Altman analyses. Two independent observers were trained separately by a nuclear physician to measure maximal periprosthetic standardized uptake values (SUVmax) for each arthroplasty component (n = 126). Findings at surgery (whether the components were well fixed or loose, as well as the presence or absence of infection) were used as a reference. Presence of periprosthetic joint infection was retrospectively determined based on the criteria suggested by the European Bone and Joint Infection Society (EBJIS): clinical features in combination with blood analysis, synovial fluid cytologic analysis, and microbiology test results. Receiver operating characteristic (ROC) curves were plotted to assess the area under the curve (AUC) for each investigated component separately, indicating suitable SUVmax thresholds that differentiate loose from well-fixed components. After excluding patients with confirmed or suspected PJI per the EBJIS criteria (n = 12), the above analysis was repeated for the remaining patients with aseptic loosening (n = 51).

RESULTS

We found higher 18F-fluoride uptake around loose versus well-fixed components in all but femoral TKA components (median [range] SUVmax for well-fixed versus loose THA cups 10 [7 to 30] versus 22 [6 to 64], difference of medians 12; p = 0.003; well-fixed versus loose TKA femoral components 14 [4 to 41] versus 19 [9 to 42], difference of medians 5; p = 0.38). We identified favorable ROC curves for all investigated components except femoral TKA components (THA cups AUC 0.81 [best threshold 13.9]; THA femoral stems AUC 0.9 [best threshold 17.3]; femoral TKA components AUC 0.6 [best threshold 14.3]; tibial TKA components AUC 0.83 [best threshold 15.8]). 18F-fluoride was even more accurate at diagnosing loosening when we limited the population to those patients believed not to have prosthetic joint infection (THA cups AUC 0.87 [best threshold 14.2]; THA femoral stems AUC 0.93 [best threshold 15.0]; femoral TKA components AUC 0.65 [best threshold 15.8]; tibial TKA components AUC 0.86 [best threshold 14.7]). We found strong interrater correlation when assessing SUVmax values, with Spearman ρ values ranging from 0.96 to 0.99 and Bland-Altman plots indicating excellent agreement between the two independent observers.

CONCLUSION

Measuring SUVmax after 18F-fluoride PET/CT is a useful adjunct in the diagnostic evaluation for suspected implant loosening after THA and TKA. The method appears to be both accurate and reliable in diagnosing implant loosening for all components except femoral TKA components. In a real-world mixed population with both low-grade infection and aseptic loosening, the method seems to be fairly easy to learn and helpful to subspecialized arthroplasty clinicians. When infection can be ruled out, the method probably performs even better. Further prospective studies are warranted to explore the reason why femoral TKA component loosening was more difficult to ascertain using this novel technique.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Association between intra-articular hyaluronic acid injections in delaying total knee arthroplasty and safety evaluation in primary knee osteoarthritis: analysis based on Health Insurance Review and Assessment Service (HIRA) claim database in Republic of Korea

BACKGROUND

The prevalence of knee osteoarthritis (KOA), a progressive degenerative disease, is gradually increasing, and it is a progressive degenerative disease. In patients with mild-to-moderate KOA, intra-articular hyaluronic acid (IA-HA) has been shown to be an effective non-operative treatment option that can provide significant pain relief and symptom improvement by increasing intra-articular viscoelasticity. This study aimed to evaluate the efficacy of IA-HA injections in delaying total knee arthroplasty (TKA) and the safety of IA-HA according to IA-HA type and combination with intra-articular corticosteroid (IA-CS) using a large health insurance claim database.

METHODS

For this retrospective cohort study, the study population included patients aged ≥ 50 years with a first diagnosis of KOA between 2009 and 2014, who underwent TKA by 2020, using the Health Insurance Review and Assessment Service claim database in Republic of Korea. IA-HA injections were categorized as single or multiple injection regimen agents. Cox proportional hazard models estimated hazard ratios (HR) for TKA risk, adjusted for covariates. Logistic regression assessed the occurrence of adverse events after IA-HA administration.

RESULTS

In all, 36,983 patients were included. Patients who received IA-HA injections had a significantly longer time to TKA compared to those who did not (mean delay of approximately 1 year). The IA-HA group had a significantly lower risk of TKA (HR: 0.61, 95% CI: 0.60-0.62) than non-IA-HA group after adjusting for covariates, which included age, sex, medical history, number of hospital beds, and CS injection. Single injection IA-HA regimen agents showed the longest time to TKA and lowest risk (HR: 0.56, 95% CI: 0.53-0.59). TKA risk decreased with the number of IA-HA cycles. Adverse events occurred in 6.7% of IA-HA cases without CS, with very low incidence of infection. Multiple injection regimen agents (multiple injection regimen 7.0% vs. single injection regimen 3.6%) and concurrent IA-CS use (concurrent IA-CS use 13.9% vs. IA-HA only 6.7%) were associated with higher infection risk.

CONCLUSION

IA-HA injections were associated with a significant delay in TKA among patients with KOA. Single-injection regimen agents had the lowest TKA risk. Infection risk increased with multiple injections and concurrent IA-CS use. These findings could suggest the use of IA-HA as an effective non-operative intervention option for managing KOA and delaying TKA. Careful selection of IA-HA type and consideration of concurrent IA-CS use could play a role in delaying the time to TKA and reducing complications.

Understanding the impact of physical activity level and sports participation on implant integrity and failure in patients following unicompartmental and total knee arthroplasty: A scoping review

Objective

Recommendations discouraging high levels of physical activity and sports following unicompartmental (UKA) and total knee arthroplasty (TKA) have been questioned in recent years. This scoping review aimed to summarize the literature examining the impact of physical activity level and sports participation on implant integrity and failure in patients following UKA and TKA.

Methods

Five databases (Medline, Embase, SCOPUS, CINAHL, ProQuest) were searched up to April 17, 2024. Retrospective, prospective and cross-sectional studies were included if they assessed the impact of physical activity level and/or sports participation (exposure variables) on implant integrity and/or failure (outcome variables) at ≥1 year following UKA or TKA. Two authors independently conducted abstract/full text reviews and data charting. Extracted data were summarized using descriptive analysis.

Results

Of 2014 potential records, 20 studies (UKA: n ​= ​6 studies, 2387 patients/TKA: n ​= ​14 studies, 7114 patients) met inclusion criteria. Following both UKA & TKA, most patients regularly participated in light to moderate physical activities and lower impact sports (e.g. walking, cycling, golf). No studies reported a deleterious effect of physical activity level or sports participation on implant integrity or failure post UKA (mean follow-up: 3.3-10.3 years). Three studies reported an association between greater levels of physical activity with increased risk of implant failure post TKA (mean follow-up: 1-11.4 years).

Conclusions

No studies demonstrated an association between greater levels of physical activity and sports participation with increased implant wear or failure post UKA, whereas results were mixed following TKA. There is a need for large, prospective cohort studies with long-term follow-up.

Radiological and clinical outcomes after Attune primary total knee arthroplasty using Stemmable Tibia: A two-year follow-up prospective bi-center study

This prospective bi-center study aimed to analyze the outcomes of primary total knee arthroplasty using the Stemmable Tibia Attune system. A total of 100 patients who underwent primary total knee arthroplasty with Stemmable Tibia from January 2019 to December 2021 were enrolled in the study. Radiological outcomes (hip-knee-ankle axis and medial proximal tibial angle) were assessed preoperatively and postoperatively. Clinical outcomes (visual analog scale score, Hospital for Special Surgery score, Knee Society function score, Knee Society knee score, flexion contracture, further flexion, and range of motion) were analyzed preoperatively and at 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively. Complications (periprosthetic joint infection and aseptic loosening) were examined. The hip-knee-ankle axis decreased (preoperative: 9.5° ± 6.3°, postoperative: 1.1° ± 2.7°), whereas the medial proximal tibial angle increased (preoperative: 84.6° ± 4.1°, postoperative: 89.8° ± 1.9°). The visual analog scale score, Hospital for Special Surgery score, Knee Society knee score, and Knee Society function score increased postoperatively. The Knee Society knee score indicated above good outcomes (100.0% and 99.0% at 1 and 2 years postoperatively, respectively). The Knee Society function score also showed above good results (98.0% and 93.0% at 1 and 2 years postoperatively, respectively). The range of motion significantly improved (p < 0.001): flexion contracture decreased from 9.10° ± 7.23° to 2.15° ± 2.87°, whereas further flexion increased from 136.05° ± 14.78° to 139.80° ± 10.02°. One patient developed periprosthetic joint infection; no early loosening was observed. In conclusion, Attune primary total knee arthroplasty with Stemmable Tibia not only is safe and effective but also leads to radiological and clinical improvements.

Effect of Adding Stem Extension to a Short-Keeled Knee Implant on the Risk of Tibial Loosening: a Historical Cohort Study

BACKGROUND

Short-keeled tibial implants may be at higher risk of aseptic loosening. Stem augmentation has been suggested to improve its fixation. We aimed to assess whether this technique could decrease the loosening rate of such tibial implants.

METHODS

We retrospectively studied the knees receiving stemmed versus nonstemmed versions of a short-keeled prosthesis. A total of 932 patients undergoing total knee arthroplasty using a Persona prosthesis with >24-month follow-up (mean 53.7) were included, of whom 212 were at high risk of loosening due to osteoporosis or high body mass index (BMI). The rate of tibial aseptic loosening in high-risk patients and in the whole cohort was compared between those with and without stem extension. Multivariable analysis was conducted to identify the risk factors of loosening.

RESULTS

In the whole cohort, in 203 knees (21.8%), a cemented short stem was used, versus 729 knees (78.2%) without. The tibial implant revision rates for loosening were 2.06% and 0.99% for nonstemmed and stemmed cases, respectively (P = 0.551). When the cohort was categorized based on the loosening risk factors, the loosening risk was significantly higher in the high-risk than in the low-risk group, regardless of stem status (log-rank test = 8.1, hazard ratio = 2.17, 95% CI = 1.78, 2.57, P = 0.005). 212 patients were at high risk of loosening, due to high BMI or osteoporosis, among whom the risk of aseptic loosening was higher when a stem was not used (log-rank = 32.1, hazard ratio = 4.95, 95% CI = 4.05, 5.86, P < 0.001). In multivariate analysis, osteoporosis, BMI ≥35, and smoking were correlated with loosening.

CONCLUSION

The failure rate was markedly lower in the stemmed group of the patients at elevated risk of aseptic loosening due to osteoporosis and/or high BMI. In the entire cohort, the risk of loosening in stemmed tibial implants was similar to the nonstemmed group. The findings support a protective role for the stem in patients at high risk of failure of the cemented tibial implant.

LEVEL OF EVIDENCE

III therapeutic.

Soft tissue laxity is highly variable in patients undergoing total knee arthroplasty

BACKGROUND

One major goal of total knee arthroplasty (TKA) is to achieve balanced medial and lateral gaps in flexion and extension. While bone resections are planned by the surgeon, soft tissue laxity is largely intrinsic and patient-specific in the absence of additional soft tissue releases. We sought to determine the variability in soft tissue laxity in patients undergoing TKA.

METHODS

We retrospectively reviewed 113 patients undergoing TKA. Data on preoperative knee deformity were collected. Data from a dynamic intraoperative stress examination were collected by a robotic tracking system to quantify maximal medial and lateral opening in flexion (85-95 degrees) and extension (-5-20 degrees). T-tests were used to assess the differences between continuous variables.

RESULTS

A valgus stress opened the medial compartment a mean of 4.3 ± 2.3 mm (0.0-12.4 mm) in extension and 4.6 ± 2.3 mm (0.0-12.9 mm) in flexion. A varus stress opened the lateral compartment a mean of 5.4 ± 2.4 mm (0.3-12.6 mm) in extension and 6.2 ± 2.5 mm (0.0-13.4 mm) in flexion. The medial compartment of varus knees opened significantly more in response to valgus stress than valgus knees in both extension (5.2 mm vs. 2.6 mm; P < 0.0001) and flexion (5.4 mm vs 3.3 mm; P < 0.0001). The lateral compartment of valgus knees opened significantly more in response to varus stress than varus knees in both extension (6.7 mm vs. 4.8 mm; P < 0.0001) and flexion (7.4 mm vs. 5.8 mm; P = 0.0003).

CONCLUSIONS

Soft tissue laxity is highly variable in patients undergoing TKA, contributing anywhere from 0-13 mm to the post-resection gap. Only a small part of this variability is predictable by preoperative deformity. These findings have implications for either measured-resection or gap-balancing techniques.

LEVEL OF EVIDENCE

Level III.

Cementless versus Cemented Total Knee Arthroplasty Using the Same Implant Design: A Mean 5-Year Follow-up Study

Cementless implant use continues to increase primarily due to increased numbers of younger and obese patients opting for primary total knee arthroplasty (TKA). Given the increased use of cementless implants, the purpose of this study was to evaluate the midterm clinical performance of cementless TKA using a highly porous tibial baseplate compared with its cemented counterpart of the same system. We conducted a retrospective case-control study of 400 patients undergoing primary TKA that included 200 patients with cementless components matched for age and body mass index (BMI) to 200 patients with cemented implants of the same implant design with a 5-year follow-up. We evaluated clinical results, complications, revisions, and overall survivorship between the cohorts. Statistical analysis was performed using student t-test and chi-square analysis. There was no statistical difference in age (64.3 vs. 64.3 p = 0.81), BMI (34 vs. 33.1 p = 0.19), preoperative Knee Society Score (KSS) function (41 vs. 32.3 p = 0.22), and preoperative KSS knee score (39.2 vs. 38.3 p = 0.54) between the cementless and cemented cohorts, respectively. The cementless group had seven revisions, while the cemented group had nine revisions (p = 0.609). The cementless group had one revision due to aseptic loosening versus five in the cemented group (p = 0.09). Postoperative 5-year KSS knee scores were 92.84 versus 91.75 (p = 0.386) and function scores were 81.81 versus 69.65 (p = 0.00004) in the cementless and cemented groups, respectively. The cementless group had survivorship of 96.5% for all-cause revision compared with 95.5% in the cemented group at 5-year follow-up (p = 0.60). Cementless TKA using a highly porous tibial baseplate showed excellent midterm results with one case of aseptic loosening at 5-year follow-up and with similar Knee Society outcome scores and survivorship compared with the cemented group. Cementless TKA demonstrated noninferiority to cemented TKA and could be used as an alternative mode of fixation in patients opting for primary TKA. Additional long-term follow-up is needed to determine if cementless TKA can demonstrate improved survivorship over cemented TKA.

Low Risk of Periprosthetic Joint Infection After Aseptic Revision Total Knee Arthroplasty With Intraosseous Vancomycin

BACKGROUND

Aseptic revisions are the most common reason for revision total knee arthroplasty (rTKA). Previous literature reports early periprosthetic joint infection (PJI) rates after aseptic rTKA to range from 3 to 9.4%. Intraosseous (IO) regional administration of vancomycin has previously been shown to produce high local tissue concentrations in primary and rTKA. However, no data exist on the effect of prophylactic IO vancomycin on early PJI rates in the setting of aseptic rTKA. The aim of this study was to determine the following: (1) what is the rate of early PJI during the first year after surgery in aseptic rTKA performed with IO vancomycin; and (2) how does this compare to previously published PJI rates after rTKA.

METHODS

A consecutive series of 117 cases were included in this study who underwent rTKA between January 2016 and March 2022 by 1 of 2 fellowship-trained adult reconstruction surgeons and received IO vancomycin at the time of surgery in addition to standard intravenous antibiotic prophylaxis. Rates of PJI at 3 months, 1 year, and the final follow-up were evaluated and compared to prior literature.

RESULTS

Follow-up at 3 months was available for 116 of the 117 rTKAs, with 1 lost to follow-up. The rate of PJI was 0% at 3 months postoperatively. Follow-up at 1 year was obtained for 113 of the 117 rTKAs, and the PJI rate remained 0%. The rate of PJI at the final follow-up of ≥ 1 year was 0.88% (95% confidence interval: -0.84 to 2.61). Previous literature reports PJI rates in aseptic rTKA to range from 3 to 9.4%.

CONCLUSIONS

Dual prophylactic antibiotics with IO vancomycin in conjunction with intravenous cephalosporins or clindamycin were associated with a substantial reduction in early PJI compared to prior published literature. These data supplement the early evidence about the potential clinical benefits of IO vancomycin for infection prevention in high-risk cases.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Revision Total Knee Arthroplasty With an Imageless, Second-Generation Robotic System

BACKGROUND

Robotic-assisted total knee arthroplasty is increasingly used in revision total knee arthroplasty (rTKA), with imageless systems recently receiving Food and Drug Administration (FDA) approval. However, there remains a paucity of literature on the use of robotic assistance in revision total knee arthroplasty (TKA). This paper describes the imageless surgical technique for robotic revision TKA using a second-generation robotic system and details both intraoperative and 90-day outcomes.

METHODS

This was a retrospective review of 115 robotic revision TKAs from March 2021 to May 2023 at 3 tertiary academic centers. Patient demographics, perioperative surgical data, and 90-day outcomes were collected. Pain and Patient-Reported Outcomes Measurement Information System scores preoperatively and postoperatively were recorded. All-cause reoperations at the final follow-up were detailed. The mean patient age was 65 years (range, 43 to 88), and 58% were women. The mean follow-up time was 13 months (range, 3 to 51).

RESULTS

The most common indications for rTKA were instability (n = 37, 32%) and aseptic loosening (n = 42, 37%). There were 83 rTKAs to a posterior-stabilized liner, 22 to a varus-valgus constrained liner, and 5 to a hinged construct. The median polyethylene size was 11 (interquartile range, 10 to 13), and 93% of patients had their joint line restored within 5 millimeters of the native contralateral knee. Within the 90-day postoperative window, there were 8 emergency department visits and 2 readmissions. At the final follow-up, there were 5 reoperations and 2 manipulations under anesthesia. There were 4 patients who required irrigation and debridement after superficial wound dehiscence, and one had an arthrotomy disruption after a fall.

CONCLUSIONS

This review demonstrates favorable intraoperative and 90-day outcomes and suggests that imageless robotic surgery is a promising modality in rTKA. Further studies comparing the longitudinal outcomes after robotic and conventional rTKA are warranted.

Predictors and Prevalence of Persistent Pain after Total Knee Arthroplasty in One-Year Follow-up

Background

Total knee arthroplasty (TKA) is one of the most common surgeries performed to reduce pain and disability in knee arthritis. Comprehension of the etiology and prevalence of persistent postoperative knee pain can help reduce this pain and identify the predictive factors leading to it. This study aimed to investigate the predictive factors and the prevalence of persistent pain after total knee arthroplasty in one-year follow-up.

Materials and Methods

This was a prospective cohort study. Demographic data including age, sex, body mass index (BMI), hospital anxiety and depression scale (HADS), and comorbidities were collected. In 242 patients, preoperative and postoperative Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores were measured before and immediately after surgery and in 3-, 6-, and 12-month intervals during follow-up. Loosening of the prosthesis was also investigated by radiographic imaging in every postoperative visit.

Result

WOMAC pain decreased from a mean (standard deviation) of 49 before surgery to 18 at 6 months and 13 at 12 months. Despite this, the prevalence of moderate-to-severe persistent postoperative pain (PPP) was 13.22% (n = 32) and 9.09% (n = 22) at 6 and 12 months lower preoperative WOMAC (odd's ratio:2.8), loosening of the prosthesis (odd's ratio:1.9), higher HADS (odd's ratio:2.1) were main predictors for PPP in TKA patients as in rheumatoid arthritis (odd's ratio:1.2).

Conclusion

Loosening of the prosthesis and higher preoperative WOMAC scores are key factors in persistent post-TKA pain. Depression and anxiety are more popular among patients with more pain after TKA. RA is more prevalent in patients with PPP after TKA.

Titanium-Titanium Junctions in the Knee Corrode, Generating Damage Similar to the Hip

BACKGROUND

Previous studies identified corrosion between the modular tibial components of total knee arthroplasty devices. However, gaps persist. Compared to the hip, damage modes that occur within taper junctions in the knee remain poorly understood. In this study, we investigated corrosion on total knee arthroplasty components with titanium-titanium junctions. We asked the following question: under typical in vivo cyclic loading conditions, will the same alloy damage modes from total knee arthroplasty devices resemble those documented in the hip?

METHODS

A total of 50 paired titanium alloy tibial baseplates and stems were collected and semiquantitatively analyzed using Goldberg corrosion scoring. To characterize damage, a subsection of moderately and severely corroded components was sectioned and imaged using scanning electron and digital optical microscopy.

RESULTS

Of the 100 device components, 95% showed visual evidence of corrosion. The initial contact area between the stem and bore generally occurred 3 mm from the stem taper base. Scanning electron microscopy revealed 4 damage modes, including oxide film formation, crevice corrosion, selective dissolution, and pitting.

CONCLUSIONS

Each of the damage modes identified in modular titanium-titanium tibial junctions was previously reported by total hip arthroplasty retrieval studies. Cumulatively, our results suggest that mechanically assisted crevice corrosion promoted this damage in vivo.

Complications and Revision Surgery in Orthopedics Focusing on Traumatology

BACKGROUND

Orthopedic traumatology, a vital component of orthopedic surgery, poses significant challenges in managing complications and necessitating revision surgeries. These challenges impact clinical outcomes, healthcare economics, and patient well-being.

OBJECTIVE

This study aimed to provide insights that informed clinical decision-making and improved patient outcomes by thoroughly examining the range of complications encountered in orthopedic traumatology. Specifically, the research focused on the indications, techniques, and outcomes of revision surgeries.

METHODOLOGY

This retrospective cohort research looked at orthopedic traumatology complications and revision procedures over a thorough two-year period from March 2021 to March 2023 at Hayatabad Medical Complex in Peshawar, Pakistan. The following information was gathered from 316 patients receiving orthopedic surgery for traumatic injuries: demographics, kinds of trauma, surgical methods, complications, indications, methods, and results of revision surgery. For data analysis, chi-square tests and descriptive statistics were used, with the goal of finding patterns and correlations within the research population.

RESULTS

The average age of the 316 patients was 42.5 years, and 64.76% of them were male (n = 192). The most frequent kind of trauma (n = 218; 69.01%) was fractures, which were mostly brought on by falls (n = 147; 46.52%). The most common surgical method (n = 138; 43.67%) was found to be internal fixation, which was followed by external fixation (n = 67; 21.20%). The most common complication (n = 78; 24.68%) was surgical site infection, which resulted in revision procedures mostly for infection (n = 68; 21.52%) and implant failure (n = 56; 17.72%). Debridement was the most often used revision approach (n = 95; 30.10%), and it was substantially correlated with surgical outcomes, such as increased function (31%) and full resolution (36%).

CONCLUSION

This research emphasizes the need to maximize patient outcomes for improved well-being and highlights the crucial role that careful care plays in managing complications and revision operations in orthopedic traumatology.

Fixation or Revision for Periprosthetic Fractures: Epidemiology, New Trends, and Projections in the United States

BACKGROUND

Periprosthetic fractures can be devastating complications after total joint arthroplasty (TJA). The management of periprosthetic fractures is complex, spanning expertise in arthroplasty and trauma. The purpose of this study was to examine and project trends in the operative treatment of periprosthetic fractures in the United States.

METHODS

A large, public and private payer database was queried to capture all International Classification of Diseases, Tenth Revision (ICD-10) diagnosis codes for periprosthetic femoral and tibial fractures. Statistical models were created to assess trends in treatment for periprosthetic fractures and to predict future surgical rates. An alpha value of 0.05 was used to assess significance. A Bonferroni correction was applied where applicable to account for multiple comparisons.

RESULTS

In this study, from 2016 to 2021, 121,298 patients underwent surgical treatment for periprosthetic fractures. There was a significant increase in the total number of periprosthetic fractures. The incidence of periprosthetic hip fractures rose by 38% and that for periprosthetic knee fractures rose by 73%. The number of periprosthetic fractures is predicted to rise 212% from 2016 to 2032. There was a relative increase in open reduction and internal fixation (ORIF) compared with revision arthroplasty for both periprosthetic hip fractures and periprosthetic knee fractures.

CONCLUSIONS

Periprosthetic fractures are anticipated to impose a substantial health-care burden in the coming decades. Periprosthetic knee fractures are predominantly treated with ORIF rather than revision total knee arthroplasty (TKA), whereas periprosthetic hip fractures are predominantly treated with revision total hip arthroplasty (THA) rather than ORIF. Both periprosthetic knee fractures and periprosthetic hip fractures demonstrated increasing trends in this study. The proportion of periprosthetic hip fractures treated with ORIF relative to revision THA has been increasing.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Cemented vs Cementless Robotic-Assisted Total Knee Arthroplasty Yield Similar Short-Term Clinical Outcomes

Background

In primary total knee arthroplasty (TKA), there is ongoing controversy about optimal fixation (cemented vs cementless). Cemented TKA remains the gold standard, with the largest body of long-term evidence available to support it. However, cementless TKA implants are gaining popularity due to potential biomechanical advantages and a growing body of literature supporting survivorship. Due to paucity of literature investigating fixation methods in robotic-assisted TKA (Ra-TKA), we aim to compare clinical outcomes of cementless Ra-TKA with those of cemented Ra-TKA.

Methods

This is a retrospective cohort study of patients who underwent Ra-TKA by 19 surgeons comparing results of cases using cementless vs cemented fixation. We observed short-term complications, emergency room visits, and readmissions. We collected patient-reported outcomes measurement information system and knee injury and osteoarthritis outcome scores preoperatively and 12 weeks after surgery.

Results

A total of 582 TKA cases were included: 335 cementless and 247 cemented. The patients in the cementless group were younger and had a higher body mass index. The cemented group had a higher rate of return to the operating room, with manipulation under anesthesia for stiffness being the most common indication in both groups. There were no statistically significant differences in 30-day readmissions, 90-day emergency room visits, or patient-reported outcomes.

Conclusions

Our retrospective study demonstrated higher return to operating room in the cemented group vs the cementless group. We reported no differences in any other short-term outcomes between the cementless and cemented Ra-TKA. Our data support efficacy and safety of cementless Ra-TKA at 3-month follow-up.

Methodological Assessment of the 100 Most-Cited Articles in Total Knee Arthroplasty in the Last Decade Compared to the All-Time List

BACKGROUND

Recent advances in total knee arthroplasty (TKA) have been driven by a growing focus on evidence-based medicine. This transition is reflected in the critical appraisal of both, the quality of work and the potential impact on the orthopedic community. The purpose of our study was to (1) identify the top 100 most-cited articles in TKA in the last decade and from all-time, and (2) compare methodological rigor of the most-cited articles in TKA in the last decade to articles all-time by level of evidence.

METHODS

The top 100 cited articles were recorded for manuscripts from the last decade, January 1, 2012 to December 31, 2022, and manuscripts from all-time for TKA. We collected authors, year of publication, journal of the article, country of origin of authors, article type (basic science article, clinical research article), level of evidence, methodological index for non-randomized studies score, physiotherapy evidence database scale, and citation density (total citations/years published).

RESULTS

The largest number of studies for all-time TKA (53.0%) and decade TKA (42.0%) were Level III. The average methodological index for non-randomized studies score for comparative studies was 18.7 for all-time TKA and 20.7 for decade TKA (P < .001). The average physiotherapy evidence database score was 6.1 for all-time TKA and 8.1 for decade TKA (P > .05). The highest citation density for all-time TKA was 111 and for past decade was 63. The number of level II studies in TKA increased from 19.0% from all time to 38.0% from the last decade (P < .05).

CONCLUSIONS

Our findings of improved methodologies over time reflect positive steps toward evidence-based practice in TKA. A continued focus on producing methodologically sound studies may guide evidence-based clinical decision-making.

[GMK rotating hinge prosthesis. A valid option for complex revision knee prosthetic surgery]

INTRODUCTION

revision joint replacement surgery presents a surgical challenge. The use of rotating hinge prostheses is an option in patients with femorotibial bone defects, ligament insufficiency, or significant deformities. The aim of this study was to evaluate the clinical, functional, and radiological outcomes of a series of patients who underwent surgery using the GMK Hinge (Medacta®) rotational hinge model.

MATERIAL AND METHODS

a descriptive, retrospective, and analytical study was conducted on a series of 36 patients, with a mean age of 72.5 years (47-85), operated on by the same surgical team between January 2015 and January 2022. The etiology of revision was chronic infection in 38.9% of cases, instability in 33.3%, aseptic loosening in 19.4%, and stiffness in 8.4%. The Knee Society Score (KSS) and the Forgotten Joint Score (FJS) were used to assess functional outcomes. The degree of femorotibial bone defect was evaluated using the Anderson Orthopaedic Research Institute (AORI) classification. Postoperative complications are also recorded.

RESULTS

a total of 36 patients, 17 males and 19 females, were included, with a mean follow-up of 30 months (12-66). Twelve patients had type 1 defects, ten had 2A defects, ten had 2B defects, and two had type 3 defects on the femoral side, with the use of wedges required for asymmetrical defects (21 patients). The predominant tibial defect was type 1 without the need for wedges. The majority achieved a satisfactory outcome on the KSS scale (72.2 ± 9.4), with significant differences compared to the previous KSS (54.3 ± 8.9). A score of 31 (12-67) was also obtained on the FJS scale. Postoperative complications were present in 16.7% of patients.

CONCLUSIONS

complex prosthetic revision surgery using a rotating hinge prosthesis represents a suitable therapeutic option, yielding appropriate clinical and functional outcomes, albeit not without complications.

A novel quantitative grading system for implant fixation in revision total knee arthroplasty

Aims

Obtaining solid implant fixation is crucial in revision total knee arthroplasty (rTKA) to avoid aseptic loosening, a major reason for re-revision. This study aims to validate a novel grading system that quantifies implant fixation across three anatomical zones (epiphysis, metaphysis, diaphysis).

Methods

Based on pre-, intra-, and postoperative assessments, the novel grading system allocates a quantitative score (0, 0.5, or 1 point) for the quality of fixation achieved in each anatomical zone. The criteria used by the algorithm to assign the score include the bone quality, the size of the bone defect, and the type of fixation used. A consecutive cohort of 245 patients undergoing rTKA from 2012 to 2018 were evaluated using the current novel scoring system and followed prospectively. In addition, 100 first-time revision cases were assessed radiologically from the original cohort and graded by three observers to evaluate the intra- and inter-rater reliability of the novel radiological grading system.

Results

At a mean follow-up of 90 months (64 to 130), only two out of 245 cases failed due to aseptic loosening. Intraoperative grading yielded mean scores of 1.87 (95% confidence interval (CI) 1.82 to 1.92) for the femur and 1.96 (95% CI 1.92 to 2.0) for the tibia. Only 3.7% of femoral and 1.7% of tibial reconstructions fell below the 1.5-point threshold, which included the two cases of aseptic loosening. Interobserver reliability for postoperative radiological grading was 0.97 for the femur and 0.85 for the tibia.

Conclusion

A minimum score of 1.5 points for each skeletal segment appears to be a reasonable cut-off to define sufficient fixation in rTKA. There were no revisions for aseptic loosening at mid-term follow-up when this fixation threshold was achieved or exceeded. When assessing first-time revisions, this novel grading system has shown excellent intra- and interobserver reliability.

Neutrophil Extracellular Trap-related Biomarkers Are Increased in the Synovial Fluid of Patients With Periprosthetic Joint Infections

BACKGROUND

The diagnosis of periprosthetic joint infection (PJI) is a major challenge in clinical practice. The role of neutrophils in fighting infection has been increasingly understood, and one mechanism of action of these cells is neutrophil extracellular traps. However, little is known about this process in PJI.

QUESTIONS/PURPOSES

(1) Are the biomarkers of neutrophil extracellular trap formation (citrullinated histone H3 [H3Cit], cell-free DNA [cf-DNA], and myeloperoxidase [MPO]) increased in the synovial fluid of patients with PJI? (2) What is the diagnostic accuracy of biomarkers of neutrophil extracellular trap formation for PJI?

METHODS

Between May 2020 and March 2021, 43 patients who underwent revision THA or TKA were enrolled in this study. Eleven patients were excluded and 32 patients were categorized into the PJI group (n = 16) or non-PJI group (n = 16) according to the 2018 Second International Consensus Meeting on Musculoskeletal Infection criteria. There were 15 men and 17 women in this study, with a median (range) age of 70 years (60 to 80 years). Twenty-seven patients had TKA and five had THA. We measured cf-DNA, MPO, and H3Cit in synovial fluid. The sensitivity, specificity, and receiver operating characteristic curve were calculated for each biomarker using the Musculoskeletal Infection Society criteria as the gold standard for diagnosis and considering a clinical surveillance of 2 years for patients in the non-PJI group.

RESULTS

Patients with PJI had higher levels of synovial fluid cf-DNA (median [range] 130 ng/µL [18 to 179] versus 2 ng/µL [0 to 6]; p < 0.001), MPO (1436 ng/µL [55 to 3996] versus 0 ng/µL [0 to 393]; p < 0.001), and H3Cit (2115 ng/µL [5 to 2885] versus 3 ng/µL [0 to 87]; p < 0.001) than those in the non-PJI group. In receiver operating characteristic curve analyses, we observed near-perfect performance for all biomarkers evaluated, with an area under the curve of 1 (95% CI 0.9 to 1), 0.98 (95% CI 0.9 to 1), and 0.94 (95% CI 0.8 to 0.99) for cf-DNA, MPO, and H3Cit, respectively. The sensitivity for detecting PJI using synovial fluid was 100% for cf-DNA, 94% for MPO, and 88% for H3Cit. The specificity was 100% for cf-DNA and MPO, and 88% for H3Cit.

CONCLUSION

Our results show that neutrophils in the periprosthetic microenvironment release neutrophil extracellular traps as part of the bactericidal arsenal to fight infection. These results allow a better understanding of the cellular and molecular processes that occur in this microenvironment, enabling the design of more assertive strategies for identifying new biomarkers and improving the available ones. Novel studies are needed to define whether and how neutrophil extracellular trap-related biomarkers can be useful for diagnosing PJI.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Can the Current Thresholds for Synovial Cell Count and Neutrophil Percentage to Diagnose Prosthetic Joint Infection be Applied to Metal-on-Metal Rotating Hinge Total Knee Arthroplasty?

BACKGROUND

Synovial leukocyte count analysis is an important tool in the diagnosis of PJI. However, results can be poor if metallosis is present. The issue of metallosis was established for some rotating hinge knee arthroplasty designs.

METHODS

This was a retrospective single-center analysis that included 108 patients who had a single-design metal-on-metal rotating hinge knee arthroplasty who underwent revision surgery and had prior synovial fluid analysis performed. The diagnostic accuracy of leukocyte count and the percentage of polymorphonuclear neutrophiles (% PMN) were investigated.

RESULTS

Patients who had a PJI had a higher median leukocyte count and % PMN compared to aseptic revisions (7,905/μL (interquartile range (IQR) 2,419 to 37,400) and 85% (IQR 70.3 to 93.8) versus 450 (IQR 167 to 1,215) and 46% (IQR 28.5 to 67.4%), P < .001). The respective areas under the curves were 0.916 (95% confidence interval 0.862 to 0.970) for leukocyte count and 0.821 (95% confidence interval 0.739 to 0.902) for % PMN. We calculated an optimal cut-off value of 1,200 leukocytes/μL (Sensitivity 94.5%/specificity 75.5%) and 63% PMN (Sensitivity 85.5%/specificity 73.6%) to define PJI. Established thresholds were less sensitive, but more specific. The "infection likely" scenario of the European Bone and Joint Infection Society (EBJIS) definition was closest to the calculated thresholds.

CONCLUSION

Currently used thresholds for leukocyte cell count and %PMN to define PJI were less sensitive and specific in the diagnosis of PJI in metal-on-metal RHK knees. Surgeons must consider lower cut-off values when evaluating such implants for PJI.

The accuracy of digital templating in the preoperative planning of total knee arthroplasties: A systematic review and meta-analysis

AIMS

Accurately predicting the implant size in total knee arthroplasties could increase the efficiency of the operation, decrease the costs associated with the procedure and result in improved patient outcomes. To substantiate its continued use, digital templating must demonstrate itself to be an accurate tool in predicting component size in order for surgeons to confidently use it to optimize the procedure.

METHODS

A systematic literature review was performed and identified 16 studies within the Pubmed, Ebsco and Ovid-Embase databases, with 1189 TKR prostheses included for analysis. A quality of evidence assessment was performed on each study depending on the study design. A random effects meta-analysis model was used to pool overall implant accuracy and the reported inter-rater agreement when performing digital templating and displayed in a forest plot. Meta-regression was used analyze potential factors that may affect the accuracy of digital templating.

RESULTS

The pooled proportion of accurate templates with 0 margin of error was found to be 56% (52-61, 95CI), which increases to 96% (0.94-0.98, 95CI) when allowing for a 1 size margin of error. Subgroup analysis between femoral and tibial components concluded no statistically significant difference.

CONCLUSIONS

This study supports the continued use of digital templating for planning total knee arthroplasties and recommends further subgroup analysis of patient age, body mass index and sex against accuracy. This review was registered in the International Prospective Register of Systematic Reviews Database under ID: CRD420222367461. No funding was provided for the completion of this systematic review.

BACKGROUND

Templating in the preoperative planning of total knee arthroplasties is a vital step in ensuring maximum operative efficiency. A method that can accurately predict the required implant size within 1 size could improve theatre turnover, decrease costs and benefit patient outcomes. The current literature on the accuracy of digital templating in total knee arthroplasties lacks a systematic review calculating the overall accuracy of the process, this study aims to address this gap.

Use of Biomaterials in 3D Printing as a Solution to Microbial Infections in Arthroplasty and Osseous Reconstruction

The incidence of microbial infections in orthopedic prosthetic surgeries is a perennial problem that increases morbidity and mortality, representing one of the major complications of such medical interventions. The emergence of novel technologies, especially 3D printing, represents a promising avenue of development for reducing the risk of such eventualities. There are already a host of biomaterials, suitable for 3D printing, that are being tested for antimicrobial properties when they are coated with bioactive compounds, such as antibiotics, or combined with hydrogels with antimicrobial and antioxidant properties, such as chitosan and metal nanoparticles, among others. The materials discussed in the context of this paper comprise beta-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP), hydroxyapatite, lithium disilicate glass, polyetheretherketone (PEEK), poly(propylene fumarate) (PPF), poly(trimethylene carbonate) (PTMC), and zirconia. While the recent research results are promising, further development is required to address the increasing antibiotic resistance exhibited by several common pathogens, the potential for fungal infections, and the potential toxicity of some metal nanoparticles. Other solutions, like the incorporation of phytochemicals, should also be explored. Incorporating artificial intelligence (AI) in the development of certain orthopedic implants and the potential use of AI against bacterial infections might represent viable solutions to these problems. Finally, there are some legal considerations associated with the use of biomaterials and the widespread use of 3D printing, which must be taken into account.

Chronic post-surgical pain after knee arthroplasty: a role of peripheral nerve blocks

Introduction

Peripheral nerve blocks are an efficient method of pain control after total knee arthroplasty (TKA), but there is no report of their impact on chronic post-surgical pain (CPSP).

Methods

This prospective observational study aimed to assess adductor canal block (ACB) and IPACK block (blocks vs. no blocks) on opioid consumption, postoperative pain score, chronic post-surgical pain 2 years after TKA.

Results

166 patients (82 vs. 84) were analyzed. Opioid consumption was less in the group with blocks (9.74 ± 3.87 mg vs. 30.63 ± 11.52 mg) (p < 0.001). CPSP was present in 20.24% of patients in the group without blocks and 6.1% of patients with blocks (p = 0.011). Predictor variables of CPSP included pain before surgery (cut-off of 5.5), pain at rest (cut-off of 2.35), pain during active movement (cut-off: 2.5), and opioid consumption (cut-off: 8 mg).

Conclusion

Peripheral nerve blocks provide adequate analgesia, significantly decrease opioid consumption, improve functional outcomes, and reduce CPSP 2 years after surgery.

The causal relationship between psoriasis and artificial joint re-operation after arthroplasty: A two-sample Mendelian randomization study

BACKGROUND

Psoriasis is observationally associated with a higher risk of complications of arthroplasty; however, the causal effects of psoriasis on complications of arthroplasty are yet to be established. This study was to explore the causal effect of psoriasis on artificial joint re-operation after arthroplasty through two-sample Mendelian randomization (MR).

METHODS

In the MR analysis, psoriasis was selected as the exposure in this study while single-nucleotide polymorphisms (SNPs) from a genome-wide association study (GWAS) were selected as the instrumental variables (IVs). Summary statistics data on artificial joint re-operation was extracted from publicly available GWAS data, including 218 792 European descent individuals. MR analysis was performed using the standard inverse variance weighted method (IVW). Furthermore, MR Egger, weighted median, simple mode, weighted mode, and the MR-PRESSO (Mendelian Randomization Pleiotropy Residual Sum and Outlier) test were also done to verify the results. Finally, the sensitivity analysis was executed.

RESULTS

The IVW showed that psoriasis increases the risk of artificial joint re-operation (OR = 1.12; 95% CI = (1.01, 1.25); p = 0.036). This outcome was also verified by other methods including weighted median (OR = 1.16; 95% CI = (1.03, 1.31); p = 0.015), MR Egger (OR = 1.22; 95% CI = (1.03, 1.44); p = 0.038), and weighted mode (OR = 1.16; 95% CI = (1.03, 1.30); p = 0.025). No heterogeneity and directional pleiotropy were observed upon sensitivity analysis.

CONCLUSION

The present study showed that psoriasis has a potential causal effect on artificial joint re-operation after arthroplasty. Further studies are warranted to elucidate the underlying mechanisms of causal associations between psoriasis on re-operation.

Restricted kinematic alignment is clinically non-inferior to mechanical alignment in the short and mid-term: A systematic review

BACKGROUND

In recent years, kinematic alignment (KA) is becoming a valid alternative to mechanical alignment (MA) in total knee arthroplasty (TKA). However, to avoid early failures, the restricted kinematic alignment (rKA) approach has been developed to restore native knee kinematics without reproducing extreme knee phenotype. This systematic review aims to evaluate clinical and radiological outcomes between rKA and MA for TKA.

METHODS

A systematic literature search was conducted following PRISMA guidelines on Pubmed, Scopus and Cochrane Library. The following search string was adopted: (((restricted kinematic) AND (mechanical)) AND (alignment)) AND (knee). We included studies that analyzed rKA versus MA in terms of clinical outcomes and complications with a minimum of 6 months of follow up. The following rKA- and MA-related data were evaluated: patient-reported outcome scores (PROMs), radiographic analysis of lower limb alignment, and complications. Criteria from the Methodological Index for Non-Randomized Studies were used to assess the methodological quality of the articles.

RESULTS

This systematic review included seven clinical studies with a total of 892 knees (471 for MA group and 421 for rKA group, respectively). Overall, post-operative PROMs were similar between rKA and MA. Moreover, rKA reached better results regarding Forgotten Joint Score and post-operative patient satisfaction. Finally, no higher complication rate was observed with the rKA approach.

CONCLUSION

The rKA aims to restore native knee kinematics, avoiding extreme deformities. Clinical outcomes are not inferior or even better for rKA compared with MA, without increasing the risk of short-middle-term implant failure. However, there is a high heterogeneity regarding the 'restricted' protocols used.

Adeno-Associated Virus-Delivered Fibroblast Growth Factor 18 Gene Therapy Promotes Cartilage Anabolism

OBJECTIVE

To determine the characterization of chondrogenic properties of adeno-associated virus type 2 (AAV2)-delivered hFGF18, via analysis of effects on primary human chondrocyte proliferation, gene expression, and in vivo cartilage thickness changes in the tibia and meniscus.

DESIGN

Chondrogenic properties of AAV2-FGF18 were compared with recombinant human FGF18 (rhFGF18) in vitro relative to phosphate-buffered saline (PBS) and AAV2-GFP negative controls. Transcriptome analysis was performed using RNA-seq on primary human chondrocytes treated with rhFGF18 and AAV2-FGF18, relative to PBS. Durability of gene expression was assessed using AAV2-nLuc and in vivo imaging. Chondrogenesis was evaluated by measuring weight-normalized thickness in the tibial plateau and the white zone of the anterior horn of the medial meniscus in Sprague-Dawley rats.

RESULTS

AAV2-FGF18 elicits chondrogenesis by promoting proliferation and upregulation of hyaline cartilage-associated genes, including COL2A1 and HAS2, while downregulating fibrocartilage-associated COL1A1. This activity translates to statistically significant, dose-dependent increases in cartilage thickness in vivo within the area of the tibial plateau, following a single intra-articular injection of the AAV2-FGF18 or a regimen of 6 twice-weekly injections of rhFGF18 protein relative to AAV2-GFP. In addition, we observed AAV2-FGF18-induced and rhFGF18-induced increases in cartilage thickness of the anterior horn of the medial meniscus. Finally, the single-injection AAV2-delivered hFGF18 offers a potential safety advantage over the multi-injection protein treatment as evidenced by reduced joint swelling over the study period.

CONCLUSION

AAV2-delivered hFGF18 represents a promising strategy for the restoration of hyaline cartilage by promoting extracellular matrix production, chondrocyte proliferation, and increasing articular and meniscal cartilage thickness in vivo after a single intra-articular injection.

No Association Between Hospital Volume and Early Second Revision Rate in Revision Total Knee Arthroplasty in the Dutch Orthopaedic Register

BACKGROUND

Revision knee arthroplasty (R-KA) is rising globally. Technical difficulty of R-KA varies from liner exchange to full revision. Centralization has been shown to reduce mortality and morbidity rates. The present study aimed to evaluate the association between hospital R-KA volume and overall second revision rate, as well as revision rate for different types of revision.

METHODS

The R -KAs between 2010 and 2020 with available data on the primary KA in the Dutch Orthopaedic Arthroplasty Register were included. Minor revisions were excluded. Implant data and anonymous patient characteristics were obtained from the Dutch Orthopaedic Arthroplasty Register. Survival analyses and competing risk analysis were performed per volume category (≤12, 13 to 24, or ≥25 cases/year) at 1, 3, and 5 years following R-KA. There were 8,072 R-KA cases available. Median follow-up was 3.7 years (range 0 to 13.7 years). There were a total of 1,460 second revisions (18.1%) at the end of follow-up.

RESULTS

There were no statistically significant differences between second revision rates of the three volume groups. Adjusted hazard ratio for second revision were 0.97 (Confidence Interval (CI) 0.86 to 1.11) for hospitals with 13 to 24 cases/year and 0.94 (CI 0.83 to 1.07) with ≥25 cases/year compared to low volume (≤12 cases/year). Type of revision did not influence second revision rate.

CONCLUSION

Second revision rate of R-KA does not seem to be dependent on hospital volume or type of revision in the Netherlands.

LEVEL OF EVIDENCE

Level IV, Observational registry study.

Cementing techniques for total knee arthroplasty in Norwegian hospitals; a questionnaire-based study

BACKGROUND

Cementing technique in total knee arthroplasty (TKA) may influence implant survival. There is limited knowledge about the results with clinically used techniques. The aim of this study was to investigate cementing techniques for TKA in Norwegian hospitals, to compare widely used techniques to recommendations from the literature, and to investigate variation within hospitals.

METHODS

A questionnaire requesting information about cementing techniques were distributed to all Norwegian orthopedic surgeons performing TKAs regularly in 2020. Data was analyzed using descriptive statistical methods.

RESULTS

We acquired 121 responses out of 257 surgeons. They were from 45 out of 56 hospitals, and at least half of the TKA surgeons from 20 hospitals, constituting 79 surgeons. All responders used pulsatile lavage. Cement application to both the tibial plateau and stem (full cementation) was practiced by 61%. Application of cement to both implant and bone was done by 70% of surgeons. Techniques to improve cement penetration were used by 86%. Only 35% of surgeons aimed to get a cement mantle thickness between 3-5 mm. Flexing the knee joint to remove excess cement was done by 82%. We found that in 55% of 20 hospitals the surgeons did not agree on the use of common guidelines in their ward.

CONCLUSIONS

The majority of the responders used recommended techniques from the literature when cementing TKA. At more than half of the eligible hospitals, surgeons disagreed about their hospitals' use of common guidelines. Focusing on developing evidence-based guidelines would be beneficial for TKA-quality.

A Case of TKA Failure in Patient with Primary Hyperparathyroidism

BACKGROUND

Primary hyperparathyroidism (PHPT) is an endocrine disorder with high serum calcium and parathyroid hormone (PTH) levels. Excessive secretion of PTH can cause bone loss and may have potential damage to implant fixation after total knee arthroplasty (TKA). However, there is currently no research or literature reporting prosthesis loosening after TKA associated with PHPT.

CASE PRESENTATION

This case report describes a TKA failure of tibial prothesis loosening associated with PHPT. The patient faced aggravated pain and difficulty in walking 6 months after the primary TKA. Further examinations showed high serum calcium and PTH levels indicating the presence of PHPT. After the surgery of parathyroidectomy, the patient received revision TKA with 3D-printed metaphyseal cone. Knee symptoms and function were finally improved.

CONCLUSION

PHPT is a risk factor for prosthesis loosening after TKA. Preoperative screening test of serum calcium and PTH levels is important to diagnose PHPT. For patients with PHPT undergoing TKA, preoperative endocrinotherapy and parathyroidectomy are recommended to improve the survival of prosthesis.

Black Patients are More Likely to Undergo Early Revision Total Knee Arthroplasty in a Matched Cohort Regardless of Surgeon Experience

BACKGROUND

Black patients are at an increased risk of aseptic revision total knee arthroplasty (TKA) when compared to White patients. The goal of this study was to determine whether racial disparities in revision TKA risk are related to surgeon characteristics.

METHODS

This was an observational cohort study. We used inpatient administrative data to identify Black patients who underwent unilateral primary TKA in New York State. There were 21,948 Black patients who were matched 1:1 to White patients on age, sex, ethnicity, and insurance type. The primary outcome was aseptic revision TKA within 2 years of primary TKA. We calculated annual surgeon TKA volume and identified surgeon characteristics such as training in North America, board certification, and years of experience.

RESULTS

Black patients had a higher odds of aseptic revision TKA (odds ratio (OR) 1.32, 95% CI 1.12-1.54, P < .001) and were disproportionately cared for by low volume surgeons (≤12 TKA/year). The relationship between low volume surgeons and risk of aseptic revision was not statistically significant (OR 1.24, 95% CI 0.72-2.11, P = .436). The adjusted odds ratio (aOR) for aseptic revision TKA in Black versus White patients varied across surgeon/hospital TKA volume category pairs, with the greatest aOR when TKA were performed by the highest volume surgeons at the highest volume hospitals (aOR 2.8, 95% CI 0.98- 8.09, P = .055).

CONCLUSION

Black patients were more likely to undergo aseptic TKA revision than matched White patients. This disparity was not explained by surgeon characteristics.

Does local infiltration analgesia in total joint arthroplasty offer any protection from prosthetic joint infections? An invitro experimental study

Many local anaesthetic agents are now reported to have anti-microbial properties in various studies, and this ability to inhibit microbial growth is not uniform. As local anaesthetics are commonly infiltrated into the surgical field for perioperative pain management, it is very important to know if this practice offers any protection against surgical site infections.

METHODS

In this study, three of the most common prosthetic joint infection-causing organisms, namely, Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli, were chosen and tested against the commonly used local anaesthetics. The suspension of each organism was inoculated onto three different Mueller-Hinton agar plates and a drop of an undiluted solution of each local anaesthetic agent is inoculated onto one of the three culture plates; vancomycin and gentamicin discs were used as controls.

RESULTS

The local anaesthetic agents tested could not inhibit the growth of any of the microorganisms. As there was no inhibition of bacterial growth in the experiment with the above three agents, further experiment with a diluted mixture was not performed.

CONCLUSIONS

It can be concluded that local infiltration of anaesthetic agents is less likely to provide any perioperative protection against prosthetic joint infections but may interfere with some diagnostic tests for microbiology.

Enhancement of the therapeutic efficacy of mesenchymal stem cell-derived exosomes in osteoarthritis

Osteoarthritis (OA), a common joint disorder with articular cartilage degradation as the main pathological change, is the major source of pain and disability worldwide. Despite current treatments, the overall treatment outcome is unsatisfactory. Thus, patients with severe OA often require joint replacement surgery. In recent years, mesenchymal stem cells (MSCs) have emerged as a promising therapeutic option for preclinical and clinical palliation of OA. MSC-derived exosomes (MSC-Exos) carrying bioactive molecules of the parental cells, including non-coding RNAs (ncRNAs) and proteins, have demonstrated a significant impact on the modulation of various physiological behaviors of cells in the joint cavity, making them promising candidates for cell-free therapy for OA. This review provides a comprehensive overview of the biosynthesis and composition of MSC-Exos and their mechanisms of action in OA. We also discussed the potential of MSC-Exos as a therapeutic tool for modulating intercellular communication in OA. Additionally, we explored bioengineering approaches to enhance MSC-Exos' therapeutic potential, which may help to overcome challenges and achieve clinically meaningful OA therapies.

Good Mid-Term Implant Survival of a Novel Single-Design Rotating-Hinge Total Knee Arthroplasty

BACKGROUND

Rotating-hinge knee (RHK) implants are an option for knee arthroplasty in cases of instability or severe bone loss. However, the revision rate can be increased compared to unconstrained implants which mandate improvements in implant design. This study investigates a novel RHK design for total knee arthroplasty (TKA).

METHODS

Retrospective analysis of a single design RHK TKA (GenuX MK, Implantcast) implanted between 2015 and 2019 including 133 patients (21 primary TKA, 112 revisions). The main indication for revision TKA was second-stage reimplantation following infection. The median follow-up amounted to 30 months (IQR 22-47).

RESULTS

In total, 13% (18/133) of patients underwent revision surgery after a mean time of 1 month (IQR 0-6). The main reason for the revision was (re-) infection in 8% of patients. All revisions were performed following revision TKA and none following primary TKA. There were no revision surgeries for loosening or instability. The revision-free implant survival of 83% was (95% CI 75-91%) after five years. A higher number of previous surgeries was associated with a greater revision risk (p = 0.05).

CONCLUSION

Revision and complex primary TKA using a single-design RHK implant results in good implant survival at mid-term follow-up although infection remains a major concern.

Cementless Versus Cemented Total Knee Arthroplasty: Concise Midterm Results of a Prospective Randomized Controlled Trial

BACKGROUND

We previously reported the 2-year results of a prospective randomized controlled trial of cementless versus cemented total knee arthroplasty (TKA) implants of the same design. The purpose of the present study was to provide concise results at intermediate-term follow-up.

METHODS

The original study included 141 TKAs (76 performed without cement and 65 performed with cement). Since then, 8 patients died and 4 withdrew. Of the remaining 129 patients, 127 (98%) were available for analysis. Survivorship analysis was performed; Oxford Knee, Knee Society, and Forgotten Joint Scores were calculated; and radiographs reviewed. Mean follow-up was 6 years.

RESULTS

The survivorship free of any revision was 100% in both groups. There were no differences between the groups in any patient-reported functional outcome measure (p = 0.2 to 0.5). However, a higher percentage of patients in the cementless TKA group were either extremely or very satisfied with their overall function (p = 0.01). Radiographically, there was no evidence of implant loosening in either group.

CONCLUSIONS

At 6 years, there were no differences between cementless and cemented TKA implants of the same design in terms of survivorship, clinical, or radiographic outcomes.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Outcomes in revision knee arthroplasty: Preventing reoperation for infection Keynote lecture - BASK annual congress 2023

Revision total knee arthroplasty (TKA) patients have a lower survival rate and lower post-surgical outcomes compared to primary TKA patients. Infection and aseptic loosening are the most common reasons for revision and re-revision TKAs, with infection accounting for nearly half of re-revision cases. To prevent infection, patient optimization addressing obesity, diabetes, malnutrition, and smoking cessation is crucial. Advancements in irrigation solutions, antibiotic-impregnated bone fillers, bacteriophage therapy, and electrochemical therapy hold promise for preventing infection. Technical strategies such as obtaining sufficient component fixation, joint line restoration, and using robot assistance may improve revision TKA outcomes. As the burden of revision TKA continues to rise, substantial efforts remain for mitigating future revision TKAs and their associated complications.

Change in Pain During Physical Activity Following Total Knee Arthroplasty: Associations With Improved Physical Function and Decreased Situational Pain Catastrophizing

Background and Objectives

Knee osteoarthritis is one of the primary causes of chronic pain among older adults and because of the aging population, the number of total knee arthroplasties (TKAs) performed is exponentially increasing. While pain reduction is a goal of TKA, movement-evoked pain is rarely assessed pre- and post-TKA. We characterized the distributions of change in pain, function, and situational catastrophizing in patients from presurgery to 3 months postsurgery and explored associations among these pre-post changes.

Research Design and Methods

This prospective study longitudinally assessed movement-evoked pain, function, and situational catastrophizing in patients with knee osteoarthritis (N = 92) using in-person performance-based tests (6-min walk test [6MWT], stair-climb test [SCT]) prior to and 3 months after TKA. Patients also completed the Western Ontario McMaster Universities Scales (WOMAC) pain and function subscales, and Pain Catastrophizing Scale, presurgery and 3- and 6-months postsurgery.

Results

Movement-evoked pain and function on performance tests significantly improved from pre- to post-TKA. Improved SCT function was associated with reduced SCT pain and catastrophizing. Similarly, reduced pain during the SCT was associated with reduced catastrophizing during the SCT. However, 6MWT function was not associated with 6MWT pain or catastrophizing; yet reduced pain during the 6MWT was associated with reduced catastrophizing during the 6MWT. Reduced movement-evoked pain during both performance tests was consistently associated with improved WOMAC function and pain, whereas improved function on performance tests was inconsistently associated with WOMAC function and pain. Notably, greater movement-evoked pain on both performance tests at 3-month post-TKA was associated with worse WOMAC function and pain at 6 months, whereas better function on performance tests at 3 months was associated with better WOMAC function, but not related to WOMAC pain at 6 months.

Discussion and Implications

Findings highlight the importance of situation-specific and in vivo assessments of pain and catastrophizing during physical activity.

Multi-functional bioactive silver- and copper-doped diamond-like carbon coatings for medical implants

Diamond-like carbon (DLC) coatings doped with bioactive elements of silver (Ag) and copper (Cu) have been receiving increasing attention in the last decade, particularly in the last 5 years, due to their potential to offer a combination of enhanced antimicrobial and mechanical performance. These multi-functional bioactive DLC coatings offer great potential to impart the next generation of load-bearing medical implants with improved wear resistance and strong potency against microbial infections. This review begins with an overview of the status and issues with current total joint implant materials and the state-of-the art in DLC coatings and their application to medical implants. A detailed discussion of recent advances in wear resistant bioactive DLC coatings is then presented with a focus on doping the DLC matrix with controlled quantities of Ag and Cu elements. It is shown that both Ag and Cu doping can impart strong antimicrobial potency against a range of Gram-positive and Gram-negative bacteria, but this is always accompanied so far by a reduction in mechanical performance of the DLC coating matrix. The article concludes with discussion of potential synthesis methods to accurately control bioactive element doping without jeopardising mechanical properties and gives an outlook to the potential long-term impact of developing a superior multifunctional bioactive DLC coating on implant device performance and patient health and wellbeing. STATEMENT OF SIGNIFICANCE: Multi-functional diamond-like carbon (DLC) coatings doped with bioactive elements of silver (Ag) and copper (Cu) offer great potential to impart the next generation of load-bearing medical implants with improved wear resistance and strong potency against microbial infections. This article provides a critical review of the state-of-the-art in Ag and Cu doped DLC coatings, beginning with an overview of the current applications of DLC coatings in implant technology followed by a detailed discussion of Ag/Cu doped DLC coatings with particular focus on the relationship between their mechanical and antimicrobial performance. Finally, it ends with a discussion on the potential long-term impact of developing a truly multifunctional ultra-hard wearing bioactive DLC coating to extend the lifetime of total joint implants.

MAKO robot-assisted total knee arthroplasty cannot reduce the aggravation of ankle varus incongruence after genu varus correction ≥ 10°: a radiographic assessment

INTRODUCTION

The objective of this study was to investigate the ankle alignment alterations after the correction of knee varus deformity in MAKO robot-assisted total knee arthroplasty (MA-TKA).

METHODS

A retrospective analysis was conducted for 108 patients with TKA from February 2021 to February 2022. Patients were divided into two groups based on MAKO robot involvement during the procedure: the MA-TKA group (n = 36) and the conventional manual total knee arthroplasty (CM-TKA) group (n = 72). The patients were divided into four subgroups according to the degree of surgical correction of the knee varus deformity. Seven radiological measurements were evaluated pre and post-surgery: mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), lateral distal tibial angle (LDTA), tibial plafond inclination angle (TPIA), talar inclination angle (TIA), and tibiotalar tilt angle (TTTA). TTTA is a quantitative representation of the extent of ankle incongruence.

RESULTS

The number of mTFA, mLDFA, and MPTA outliers in the MA-TKA group was significantly lower compared to the CM-TKA group (P<0.05). Knee varus deformity was properly corrected and the mechanical axis was restored in all patients, regardless of the treatment group. Only for varus corrections ≥ 10° did TTTA change significantly (p < 0.01) and ankle varus incongruence aggravate post-operation. The ΔTTTA correlated negatively with ΔTFA (r=-0.310,P = 0.001) and correlated positively with ΔTPIA (r = 0.490,P = 0.000). When the varus correction was ≥ 7.55°, the probability of ankle varus incongruence exacerbation increased 4.86-fold.

CONCLUSION

Compared with CM-TKA, MA-TKA osteotomy showed more precision but was unable to reduce post-operation ankle varus incongruence. When the varus correction ≥ 10°, ankle varus incongruence aggravated, while when the varus correction ≥ 7.55°, the probability of ankle varus incongruence increased 4.86-fold. This may occasion the pathogenesis of ankle pain following TKA.